Barium titanate thin films are grown by atomic layer deposition (ALD) at 340°C from barium cyclopentienyl and titanium methoxide precursors. H 2 O is used as the oxygen source. Binary reactions of Ba( t Bu 3 C 5 H 2 ) 2 and H 2 O are first studied separately in BaO deposition and are found to result in a hydration/dehydration cycle, which is strongly influenced by the process temperature. Self-limiting growth of amorphous barium titanate films becomes possible when Ti(OMe) 4 -H 2 O growth cycles are mixed as well as possible with Ba( t Bu 3 C 5 H 2 ) 2 -H 2 O cycles. The as-deposited amorphous films are crystallized by post-deposition annealing at 600°C. Permittivities of 15 and 70 are measured for as-deposited and post-deposition annealed films, respectively. A charge density of 1.9 lC cm -2 (equivalent oxide thickness of 1.8 nm) and leakage current density ≤ 1 × 10 -7 A cm -2 were achieved at 1 V bias with a 32 nm thick Ba-Ti-O film in a Pt electrode stack annealed at 600°C.

Bismuth silicate thin films were deposited using atomic layer deposition (ALD) with a novel precursor, Bi(CH 2 SiMe 3 ) 3 , serving as both bismuth and silicon source. Precursor synthesis, analysis, and crystal structure are also reported. Bi(CH 2 SiMe 3 ) 3 forms hexagonal crystals with a = 10.7110(11) , b = 10.7110(11) , c = 10.2500(7) ; space group P6 3 . The deposition temperature of thin films was 200±450 C, where a constant growth rate of 0.4 per cycle was obtained between 250 C and 350 C. Impurity levels of bismuth silicate films deposited at 250 C were below 0.2 at.-% and 0.1 at.-% for carbon and hydrogen, respectively. The as-deposited films were amorphous, and post-synthetic annealing in an atmosphere of N 2 or O 2 at 400±1000 C was applied.

No abstract

No abstract